AC2.1 - biological theories

William Sheldon’s somatotype theory (physiological) - what is it about?

• Sheldon saw criminals as physically different from non criminals

• In his view certain somatotypes (body types) are linked to criminal behaviour

• his key idea is that somatotype is related to criminality, e.g. mesomorphs are more likely than other to commit crime

what were the 3 types of somatotypes Sheldon identified?

• endomorphs

• ectomorphs

• mesomorphs

What are ectomorphs?

• thin and fragile

• lack both fat and muscle

• flat chested

• narrow hips and shoulders

• thin face

• high forehead

• personality - self conscious, fragile, inward looking, emotionally restrained and thoughtful

What are ectomorphs?

• thin and fragile

• lack both fat and muscle

• flat chested

• narrow hips and shoulders

• thin face

• high forehead

• personality - self conscious, fragile, inward looking, emotionally restrained and thoughtful

What are mesomorphs?

• muscular and hard bodied

• very little fat

• strong limbs

• broad shoulders

• narrow waist

• personality - adventurous, sensation seeking, assertive and domineering, enjoy physical activity

According to Sheldon which somatotype is most likely to commit crime and why?

Sheldon argued that mesomorphs are the somatotype most likely to engage in crime. They are more likely to be attracted by the risk taking it involves and their imposing physique and assertiveness can be importantly assists in crime

What are two strengths of Sheldon’s theory?

• other studies such as Glueck and Glueck 1956 have replicated Sheldon’s findings, they found that 60% of the offenders in their study were mesomorphs

• the most serious delinquients in Sheldon’s sample were the ones with the most extremely mesomorphic body shapes

What are two limitations of Sheldon’s study?

• Glueck and Glueck found that criminality was best explained not by biology alone, but by a combination of biological, physiological and environmental factors. Criminal may develop a mesomorphic build as a result of needing to be physically tough to succeed. If so, criminality causes somatotype, rather than somatotype causing criminality

• Cannot explain criminals who had endomorphic or ectomorphic shapes

Jacob’s XYY theory (genetic) - what is it about?

• believes that some crime might be due to chromosomal abnormality, 44 out of the 46 chromosomes determine the shape and constitution of our body, the other 2 determine sex

• females are known as XX

• males are known as XY

• chromosomal abnormalities may occur, some may result in the presence of an extra chromosome, one of these abnormalities is known as XYY syndrome (the presence of an extra Y chromosome)

What is XYY?

• XYY syndrome has been labelled as ‘super male syndrome’

• Men with XYY tend to be very tall, well built, and of low intelligence

• They are also said to be more aggressive and more in lines to be violent than men who only have one Y chromosome

What is evidence that supports the view that the XYY syndrome can be a cause of criminality?

• based on studies of imprisoned criminals, such as those in secure psychiatric hospital, where a higher than average proportion of inmates where fiend to have XYY syndrome, many of these had history of aggression and violent assault. Prince and what more found XYY males to be immature and unstable, with a string tendency to commit seemingly motiveless property crimes

What are 2 strengths of XYY syndrome?

• jacobs et al found an association between XYY syndrome and offenders imprisoned for violent behaviour - 15/1000 is a substantial figure, helping to provide credibility to the theory

• Prone and what more found some links between the syndrome and property crimes

What are two limitations of XYY?

• the theory may be over representative - XYY makes tend to have low intelligence compared to XY males, meaning that they are more likely to be caught, therefore skewing samples drawn from prisoners

• Genetic abnormalities are prevalent in society but don’t signal aggression